1. Field of the Invention
The present invention relates to a stator structure and a resolver.
2. Description of the Related Art
Conventionally, there is known a resolver that detects a rotation angle of a rotating electrical machine such as a motor and an electrical generator. The resolver is constituted of a stator core provided with a plurality of teeth that radially extend from an inner periphery of a ring-shaped main body part, and a rotor arranged to be opposite to the teeth in the inside of the stator core, for example. A winding is wound around each of the teeth with insulators interposed therebetween. The winding is constituted of an excitation winding to which excitation current is supplied from the outside, and two output windings that output two phase signals in accordance with the rotation angle of the rotor.
When a current is supplied to a winding of the rotating electrical machine that is target for detecting the rotation angle of the resolver, a part of a magnetic flux generated from the winding of the rotating electrical machine is superposed on a signal flowing through the excitation winding wound around a stator of the resolver or a signal output from the output windings so as to strain a wave shape of the signal. Therefore, there exists the possibility that angle detection accuracy of the resolver is reduced and a rotation position of the rotating electrical machine is not able to be detected precisely. Thus, there is proposed a resolver that is able to reduce effects of magnetic noise (magnetic flux) from the outside (see, for example, Japanese Patent No. 5970355).
A stator structure of a resolver as disclosed in Japanese Patent No. 5970355 is constituted of an electromagnetic shield provided with a ring-shaped shield body covering a plurality of teeth. In this stator structure, a stator core has a core fastening part in which core fastening holes are formed as bolt fastening holes. The electromagnetic shield has a shield fastening part in which shield fastening holes are formed as bolt fastening holes aligned with the core fastening holes. The stator structure is constituted so that the core fastening part is fastened with the shield fastening part by using the core fastening holes and the shield fastening holes.
However, the stator structure of the resolver as disclosed in Japanese Patent No. 5970355 has a configuration in which the electromagnetic shield covers the teeth on one surface side of the stator, and thus the magnetic flux from the outside enters the inside of the stator from the other surface side of the stator in some cases. Thus, there exists possibility that the angle detection accuracy of the resolver is reduced not to be able to precisely detect the rotation position of the rotating electrical machine. Furthermore, the stator core and the electromagnetic shield are in contact with each other, the magnetic flux from the outside may enter the inside of the stator through the electromagnetic shield.